earticle

영어

Purpose: This study compared the muscle activity of the infraspinatus, posterior deltoid, serratus anterior, and the infraspinatus/posterior deltoid muscle activity ratio under three conditions (manual resistance, 4 kg dumbbell, 1 kg dumbbell) during shoulder lateral rotation exercises. Methods: Fifteen healthy adult males performed shoulder lateral rotation exercises under three conditions in random order. Statistical analysis was conducted using repeated measures analysis of variance, with the significance level set at ≤0.05/3 using the Bonferroni correction method. Results: Muscle activity of the infraspinatus and serratus anterior was significantly higher in the manual resistance condition compared to the other two conditions (p<.05). Posterior deltoid muscle activity was significantly higher in the 4 kg dumbbell condition compared to the other two conditions (p<.05). The infraspinatus/posterior deltoid muscle activity ratio was significantly higher in the manual resistance and 1 kg dumbbell conditions than in the 4 kg dumbbell condition (p<.05). Conclusion: Manual resistance during shoulder lateral rotation exercises selectively strengthens the infraspinatus and increases serratus anterior muscle activity, contributing to dynamic stabilization of the shoulder.